Modified Central LeadModified Central Lead (MCL1) - The modified central lead is created by placing the positive electrode at the 4th intercostal space just to the right of the sternum and the negative electrode below the left clavicle near the shoulder. The... (MCL1) – The modified central lead is created by placing the positive electrode at the 4th intercostal space just to the right of the sternum and the negative electrode below the left clavicle near the shoulder. The ground electrode (red) electrode can be placed anywhere on the body.
Einthoven’s three lead system is the most commonly used three lead cardiac monitoring system today. Some centers, though, choose to use a modified central lead (MCL1) as part of the three lead system. This is sometimes also referred to as the modified chest lead. This lead is often used together with lead II to help distinguish between supraventricularLocated above the ventricle – includes the bundle of His, AV node, atria and the SA node. 1. Six Second ECG Guidebook (2012), T Barill, p. 206 and ventricular tachycardias.
The modified central lead is created by placing the positive electrode at the 4th intercostal space just to the right of the sternum and the negative electrode below the left clavicle near the shoulder. The ground electrode (red) electrode can be placed anywhere on the body.
Whether the standard or a modified version of the three lead system is used, there is an important point to consider. Practically any lead will suffice for dysrhythmia monitoring. For tasks such as myocardial ischemiaInsufficient supply of oxygen to meet the oxygen demands of tissue. Anaerobic metabolism becomes increasingly important during periods of ischemia. Ischemia results from an inadequate blood flow that fails to meet the oxygen demands (energy demands) of tissues. If tissues... monitoring, though, each lead provides information specific only to the region viewed. For example, Lead I can provide signs of left ventricular ischemia, but only rarely signs of right ventricular ischemia.
For example, take a patient experiencing cardiac ischemiaThe ability to identify cardiac ischemia, injury and infarction is vital in the management of the majority of cardiac emergencies. Most sudden cardiac deaths are associated with an ischemic episode. Patient deaths due to an acute myocardial infarction (MI) typically... of the inferior region. In all leads, a sinus rhythmAlso known as regular sinus rhythm or sinus rhythm, this cardiac rhythm is not a dysrhythmia; sinus rhythm originates in the sinoatrial (SA) node with a rate of 60-100/minute; P waves are upright in most leads and the QRS is... is identified. But evidence of ischemia – typically found in the inferior leadsThe inferior leads show the inferior aspects of the heart - the inferior aspects of the right ventricle and the left ventricle. Much of the inferior view of the heart is of the right ventricle. Precordial leads placed along the... II and III, may be absent in lead I. If only lead I was monitored, this ischemic event would most likely be missed entirely (about 70-80% of all ischemic episodes occur with no symptoms). The bottom line: the more lead viewsLocating the positive electrode is crucial to determining which area of the heart is viewed electrically. Metaphorically, the positive electrode serves as a mini-video camera aimed at the heart in the direction of the negative electrode. These leads and their... monitored, the better.
The modified central lead, called MCL1, is established with the cardiac monitor set to lead I, with the white electrode a negative polarity, the black electrode a positive polarity (the red electrode serves as the ground). Lead MCL1 will be similar to the precordial leadThe precordial leads are attached to the chest beginning with V1, placed at the 4th intercostal space (ICS) to the right of the sternum. Lead V2 mirrors V1, but to the left of the sternum. Lead V4 is placed along... V1. Note that lead V1 is superior to lead MCL1 as a diagnostic lead for dysrhythmiasUsed interchangeably with arrhythmia, refers to any abnormal rhythm – not normal sinus rhythm or sinus tachycardia. 1. Six Second ECG Guidebook (2012), T Barill, p. 196 and for myocardial ischemia monitoring.
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 68